title: Dietary supplementation with zinc oxide stimulates ghrelin secretion from the stomach of young pigs.
abstract: Dietary supplementation with zinc is known to enhance food intake and growth in young children. However, the underlying mechanisms remain largely unknown. Ghrelin, a peptide derived mainly from stomach, plays an important role in food-intake regulation. The present study was conducted with the piglet model to test the hypothesis that zinc may increase gastric ghrelin secretion. In Experiment 1 (Exp. 1) , thirty-six 28-day-old weaned pigs were assigned to two groups (18 pigs/group), receiving four-week supplementation of 0 or 2000 mg/kg Zn (as ZnO) to the basal diet containing 100 mg/kg Zn. In Experiment (Exp. 2), sixteen 28-day-old piglets were assigned to the same treatments (n=8/group) as in Exp. 1, except that they were pair-fed an equal amount of diet. At the end of the experiments, blood, stomach and duodenum samples were obtained for biochemical analysis, including assays of ghrelin protein and insulin-like growth factor-I (IGF-I) in plasma, as well as quantification of ghrelin and IGF-I mRNA levels in the duodenum and gastric mucosa. Further, gastric mucosal cells from unsupplemented piglets were cultured with 0-0.5 mM ZnO for 2-24 h for assays of ghrelin production and gene expression. Dietary Zn supplementation increased plasma concentrations of ghrelin, IGF-I and cholecystokinin; IGF-I gene expression in the duodenum as well as food intake and piglet growth (Exp. 1). The effects of ZnO on plasma levels of ghrelin, intestinal IGF-I expression and piglet growth were independent of food intake. Addition of ZnO to culture medium enhanced ghrelin production from gastric mucosal cells without affecting ghrelin mRNA levels. Collectively, our results indicate that ZnO stimulates ghrelin secretion from the stomach at the post-transcriptional level. This novel finding aids in elucidating the cellular and molecular mechanism for a role of zinc in promoting food intake and growth of young children.
authors.affiliation: National Key Laboratory of Animal Nutrition, College of Animal Science, China Agricultural University, Beijing 100094, PR China. yinjd@mafic.ac.cn
authors.forename: Jingdong
authors.initials: J
authors.lastname: Yin
authors.forename: Xilong
authors.initials: X
authors.lastname: Li
authors.forename: Defa
authors.initials: D
authors.lastname: Li
authors.forename: Tao
authors.initials: T
authors.lastname: Yue
authors.forename: Qian
authors.initials: Q
authors.lastname: Fang
authors.forename: Jianjun
authors.initials: J
authors.lastname: Ni
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhou
authors.forename: Guoyao
authors.initials: G
authors.lastname: Wu
mesh_terms: D000821:Animal Feed; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D019587:Dietary Supplements; D004386:Duodenum / Q000378:metabolism; D005247:Feeding Behavior; D005753:Gastric Mucosa / Q000378:metabolism; D054439:Ghrelin / Q000235:genetics / Q000378:metabolism*; D006128:Growth; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D013270:Stomach / Q000166:cytology / Q000187:drug effects*; D013552:Swine; D015034:Zinc Oxide / Q000008:administration & dosage* / Q000494:pharmacology
chemical_list: D017931:DNA Primers; D054439:Ghrelin; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D015034:Zinc Oxide